import java.util.Arrays;
import java.util.Scanner;


public class Main1221 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] arr = new int[n];
        for (int i = 0; i < arr.length; i++) {
            arr[i] = sc.nextInt();
        }
        Arrays.sort(arr);
        double count = 0;
        for (int i = arr.length - 1; i >= arr.length - 5; i--) {
            count += arr[i];
        }
        System.out.println(String.format("%.1f",count / 5));
    }
}
